On controlling the propagation characteristics of microstrip transmission lines using embedded micron-sized particles and static h-fields

Methods to control the propagation characteristics of printed microstrip transmission lines (TLs) has many uses in phased-array scanning, tunable apertures and reconfigurable antennas. In this paper, a unique method of changing the propagation along a microstrip TL with multiple magneto-static responsive structures (MRSs) is introduced. Each individual MRS is sub-wavelength in size and does not require a directly connected biasing circuit. In particular, the MRS consists of two parallel conducting planes separated by a dielectric material (forming a capacitor) and a cavity with micro particles that can be orientated/aligned (i.e., moved) using magneto-static fields. The particles can thus be manipulated using biasing fields such that the two conducting planes can then be connected and disconnected, changing the MRS state between capacitive (disconnected) and inductive (connected). The simulation and measurement results in this paper show that the effective permittivity of a 50Ω microstrip TL can be changed using MRSs.